1. Modelling the Management and Dynamics of
Grass- and Croplands Across Scales
A Workshop of the CarboEurope Project, May 17-19, 2006
Jean-François Soussana Pete Smith John Tenhunen
Grassland Ecosystems Agricultural Ecosystems Integration Component
Uncertainties in European CO2 Exchange Estimates:
1. Spatial Aggregation of Ecosystem Properties
2. Merging of Land Cover and Land Use
(Near Natural versus Managed)
3. Phenology and Seasonality

2. General
Data Association
in PIXGRO

4. PIXGROfine Landuse Categories
Near-Natural
Ecosystems
2 Types for
Short-statured
Vegetation
3 Types for
Open Woody
Vegetation
8 Types for
Closed Forest
Root Crop
Maize C4
Summer Crop
Winter Crop
Final
Europe Level Exchange
Mowed
Grassland
Combined
Crops
Managed
Ecosystems
PIXGROfine Landuse Categories

5. Average PIXGROfine Response Across Europe
2002
2003
Root Crop
Maize C4
Summer Crop
Winter Crop 4 8 12
120
240
360
GPP, g m-2 d-1
Combined
Crops
Mix according
to cover and
management
Final
numbers

6. Regional cultivation Cereals Maize Olives
France is the largest cereal producer in the EU, folllowed by Germany and Poland. Together they account for more than half of of total production [1]
Over 60% of the domestic use of cereals in the EU-15 is animal feed and seed use [2] .
Source: based on Eurostat 2005, 2006

7. JRC
Country
Map
plus

8. Net C storage (NBP) vs. total herbage use by cutting and grazing
Crops and Grasslands are the Sensitive Part of the System
(Soussana et al., submitted)

9. Phenology BGC Model internal phenology (White et al. 1997)
Phenology, e.g, springtime greenup, is estimated according to Zhang et al considering chilling time and heat sums.
BGC Model internal phenology (White et al )
Variable phenological signals between the years
Two types of grasslands
Cool and warm
Differ in their onset and offset temperature thresholds
Grass onset f(T,Precip):
Strongly controlled by temperature
Longterm Taverage
Longterm annual Precipaverage
Grass offset f(T,Precip):
Strongly controlled by precipitation month before and temperature threshold
Nov. 1
Threshold
TDD
Heat sum Cd

12. Conclusion:
To reduce uncertainties, existing modelling tools require better formulation and representations for:
1. Spatial Aggregation of Ecosystem Properties
2. Merging of Land Cover and Land Use
(Near Natural versus Managed)
3. Phenology and Seasonality
This requires:
1) an organized exchange of information (Crops and Grasslands Workshop II),
2) a concerted effort to prepare supporting data, and
3) evolution of our current ecosystem modelling tools.